Hello all,

I'm flying a Tarot hexa over a forest, in a mountain region at around 3000 meters altitude

After some time flying, device start to oscillate in altitude, down , up, down up, and yesterday 
crashed in a cup of a 30 meters pine ( i called to a Climber specialist to down the copter) .

can you please help me to identify what is happen here?

I'm using a Hobbiking HK pilot, can i suspect of barometer problem? need to replace for a
original pixhawk?

Please helpme , check the log.

In this log you will see RADIO FAILSAFE, but is set to "continue with mission", so this doesn't matter.

Thank in advance, regards

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it seems like your motor #4 is not performing well.   , and so #3 is reduced to maintain attitude.

You are flying at >70 % throttle, so there is no headroom for defective motor/no redundancy. 

The condition comes and goes, so maybe maybe ESC is going into thermal protection or something like that.

there is no problem with the sensor.

Hello, Andre, and thank you very much for your answer.

Can you please tell me how you identify this ? or how can i check motors performance or fail?

What log values i need to check or compare?

I will replace this for a new motor, and check/replace ESC too.

After replacement, what is the best way to check ESC/motors without a lot of risk?

I'm loading 3.5 kg in copter (lidar/inertial/camera, and aluminium mounting base).

Thank in advance

Regards

Cristian

 

Plot ThrOut (throttle out in %) , you will see demand go 100% .

plot RCOUT.RC1..6  , you will notice #4 being often commanded to 100% , while #3 (opposite) is relaxed.

Hi Andre, how are you?
I changed motor and ESC #4, and i loaded 3,8 kg, using 2 batteries to simulate the payload (to dont load the lidar and cameras, please see attach).

Today fly at 2800 meters in a field test and again same problem, when i see problem, i do a RTL and landed without problem.
Motors are hot after landing, my configuration is:

ESC Hobbywing XRotor PRO 50A
Motors: Tarot 5008 kv 340
Props: 1855

I really dont know what can i do to load this weight without problems, can you recommend me motors and ESC for heavy lift?
i can replace all if needed.

My goal is to fly at 3000 meters loading around 4 kg without problems.

Thank in advance, attached today log.

Regards!
Cristian

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Here you can see how hard motor 2 , and especially #4 works, being maxed out most of the time.

 

here is throtle demand vs altitude.   everytime "something happens" , throttle demand is 100% , but the UAV is sinking , then "it goes away" , and you can see it climb at a "normal" throttle demand.

the symptoms are also very consistent with a ESC that goes into thermal protection. 

you can hover, /fly it for a shorter time, and check ESC temperature.  (although I've seen cool ESC's fail - because poor thermal conductivity between FET's and cooling fin)

Also: you average throttle level for a normal part of the flight is 71.9%    that means you have no real redundancy - if you are over sea, and hit a seagull, (or whatnot) - you will start to loose altitude.

provided that you are happy to fly at 71% throttle , I would recommend more powerful ESC's   (unless your are buried deeply, and don't get enough airflow)

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Hi Andre, and thank you very much for your answer.


Can you please recommend me powerful or best ESC's for my hexa? I' currently using Hobbywing XRotor PRO 50A.

I ask they,but they say ESC are not the,problem, i can accept any brand you recommend for replace all.

Thank in advance.

Cristian

your motor/prop config is expected to draw max ~32A @ 6s.   - so I'd say there is no good reason for it to be an ESC problem, yet there are two things to check out:

1.: if you run each motor as a test for xx seconds at 100% , are they about equally warm, and pull about the same amount of current ?  (requires a current sensor)  

2: there may still be an issue of bad thermal connection between a FET and a heatsink/heat spreader.

As a test, you can use even simple ESC's like those: https://hobbyking.com/en_us/turnigy-multistar-45-amp-multi-rotor-br...  - should be good value. 

On the higher-end, I do have good experience with JETI /Hacker , - but the price point is not easy to explain. 

https://www.hacker-motor-shop.com/Speed-controller/MasterMezon/Mast...

For high end machines and payloads, at least you get a max current / temperature record - in your case, I would rather invest in more thrust and redundancy first.   Having a log of a failing motor sucking high currents is fine, but won't help to save the day :)

Hi Andre, thank you very much for your answer.
Regarding tests: 

In test 1 i will need a amperimeter like attached, and test in each arm ?

In test 2, you can see the original ESC in 
https://hobbyking.com/es_es/hobbywing-xrotor-pro-50a-muti-rotor-esc...

And how i installed in attached file, how can i check thermal connection? its a sealed unit...


Wow, hacker ESC have a affordable price!  :-|
Thank you, regards

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1: no , you can use the current sensor in your copter(plot mavlink data), while running motortest.   the one you attached is for AC current , the brushless ESC output is kind of that, but also PWM modulated and at very different frequency range than the instrument is made for. measuring on the DC side is easier.

2: exactly, it's a sealed unit, so it's no foolproof way to check it.   you can use a radiometric thermal camera, and start with all ESC's at a certain temperature, run each for 30sec of heavy load  - and see temperature increase,  - or just test if they can sustain rated current in a test run (mount the airframe, apply 100% throttle to one motor at a time, then see if it's running fine for 10 minutes.) 

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